1. Field of the Invention
The present invention relates to the field of communication devices and more particularly, to communication devices for acoustic coupling to a telephone handset for transmitting information thereto, and receiving information therefrom.
2. Prior Art
The preferred embodiment of the present invention is directed to an acoustic coupler for coupling to the handset of a telephone for purposes of digital communication over the phone line and accordingly, the prior art with respect thereto will be described herein. It is to be understood however, that the invention is not necessarily so limited, as the coupler could also be used to couple voice or synthesized voice to and/or from a telephone handset, or may be combined with an integral modem to provide full modem capabilities, by way of specific example.
For many years it has been common to use modems for digital communication over phone lines between a central computer and remote terminals, such modems of course being modulator-demodulator sets for modulating the digital information in some manner so as to be transmitted within the frequency range of conventional phone systems. Such devices may either directly connect to the phone line to directly send and receive electrical signals, or may be acoustic coupled to the telephone handset to acoustically couple signals to and acoustically receive signals from the handset. While direct connect devices have certain advantages (i.e., lack of deterioration by the acoustic devices) and the newer modular plug phone systems very easily allow direct connecting to the phone line, there is still a large percentage of installed phone systems which do not readily allow such direct connect devices. Consequently, there is, and will remain for some time yet, a very substantial market for acoustic couplers and acoustic coupled devices.
In the prior art, acoustic couplers, whether separate devices or integral with a modem, have been generally characterized as having a rigid body supporting a microphone and speaker in the appropriate orientation with some form of soft, flexible and/or elastic member over the speaker and microphone in such a disposition as to mate with the face of the mouthpiece and earpiece of the conventional telephone handset. Such couplers work well where the dimensions of the handset are well known, though depending upon the shape and flexibility of the members directly contacting the mouthpiece and earpiece of the handset, have very little capability of accomodating any significant variations therein. In particular, even with the so called conventional handsets relatively large variations in the actual dimensions thereof may be encountered, particularly in foreign countries, an important consideration in that the market for the type of device being herein discussed is a very international market. In addition, in recent years, the various telephone companies, including the independent phone equipment companies, have offered a variety of phone configurations such as, by way of example, the Princess type phone which, while having a mouthpiece and earpiece disposed so as to be oriented adjacent a user's mouth and ear respectively, have a configuration of the mouthpiece and the earpiece surface, as well as the separation and angularity between the mouthpiece and earpiece of the phone which differ substantially from design to design. It is these various configurations which heretofor the prior art acoustic couplers, whether incorporating a modem or not, could not accommodate.